Comment by moyix

The relevant search term is "stylometry". One particular paper I remember is from Dawn Song's group at Berkeley a couple years back:

http://www.cs.berkeley.edu/~dawnsong/papers/2012%20On%20the%...

There's a lot of public work on the topic, but it looks like right now the best place to look is still in academic papers (I don't know of any open source libraries, for example).